Hi, I'm trying to consume events from my view-model in fragment and I can't realize why app is crash...

# coroutines

[Jan Skrasek]

Hi, I'm trying to consume events from my view-model in fragment and I can't realize why app is crashing:

2019-10-09 14:49:52.581 4418-4418/my.app.id E/AndroidRuntime: FATAL EXCEPTION: main
    Process: my.app.id, PID: 4418
    kotlinx.coroutines.JobCancellationException: Job was cancelled; job=SupervisorJobImpl{Cancelled}@b43ae6d

val myEvent = Channel<Unit>(Channel.RENDEZVOUS)

viewModel.myEvent.consumeAsFlow()
	.onEach {
		Toast.makeText(requireContext(), R.string.error, Toast.LENGTH_LONG).show()
	}
	.launchIn(lifecycleScope)

1. it is not obivous what caused the crash from the stack trace; emiting to closed channel?
2. how can I workaround it?

[Paul Woitaschek]

lifecycleScope.launch {
  consumeAsFlow.collect { Toast() }
}

[Adam Powell]

1. Looks that way, consumeAsFlow will cancel the channel when collection stops, and the lifecycleScope will be cancelled when your fragment is destroyed.
2. What behavior do you want here?

[Adam Powell]

What is the nature of myEvent?

[Paul Woitaschek]

https://kotlinlang.slack.com/archives/C1CFAFJSK/p1570522502447200

[Jan Skrasek]

Actually I'm looking for channel which will deliver the value only once. Hence consumeAsFlow seemed ok. (This is AFAICT different to PublishSubject), so I've tried randevous channel. Though I think it's not ideal (despite the crash) because new activity after rotation can miss the event in the time inbetween.